Electrical connectors are provided in a wide variety of configurations and generally are provided in sets (i.e. pairs) of connectors, such as male and female connectors, which are used to interconnect terminating ends of electrical circuitry. The connectors mount a plurality of terminals or contacts which interengage when the connectors are mated. Most often, the terminals or contacts are terminated to discrete wires or to circuit traces on a printed circuit board and which must be properly interconnected. For instance, in hard wired circuitry, a "hot" wire must be interconnected with a corresponding hot wire, a neutral wire must be interconnected with a corresponding neutral wire and a ground wire must be interconnected with a corresponding ground wire. In certain electronic applications, various signal circuitry must be properly interconnected with corresponding signal circuitry through the mating connectors. Consequently, it has been common to polarize a set or pair of mating electrical connectors so that they can be mated in only one orientation in order to properly polarize the electrical wiring or circuitry therethrough.
In order to properly understand the invention herein, the term "polarization" is understood to define structures whereby a single set or pair of electrical connectors can be mated in only one orientation as described above, such as in only one of two 180.degree. orientations. The term "keying", on the other hand, is meant to describe a system wherein one connector of any given set or pair thereof cannot be mated with another connector of another set or pair thereof, regardless of orientation.
Heretofore, there have been a variety of different polarization schemes or structures. For instance, a set or pair of electrical connectors may have keys and slots or other shapes on the outside surfaces of the connectors so that the connectors can be polarized and mated in only one of two 180.degree. orientations. Another scheme utilizes silos projecting from a connector housing and within which the terminals or contacts are mounted. The silos are received in receptacles of the mating connector. The silos and receptacles have a particular cross-sectional shape which allow the connectors to mate in only one of two 180.degree. orientations.
However, there are electrical connector systems wherein a plurality of sets or pairs of mating electrical connectors are provided of similar configurations, such as generally rectangular configurations, and wherein each set of connectors mounts a different number of pairs of terminals or contacts. In such systems, although the connectors in any given set thereof are polarized in order to ensure proper mating, there is a danger that one connector of any given set will be mated with a connector of a different set. In other words, one set or pair of mating connectors may have only one pair of terminals or contacts. That set of connectors would interconnect two circuits. Another set of mating connectors may have two pairs of terminals for interconnecting four circuits. The sets of connectors may increase in "size" to include three pairs of terminals for interconnecting six circuits, four pairs of terminals for interconnecting eight circuits, and so on. In other words, the size of the connectors are determined by the number of interconnected circuits, and such connectors are manufactured, sold and/or made available in the connector industry as an identifiable "Series" or "Line" of electrical connectors. There is a need for providing a keying system for such electrical connector systems whereby a connector in any given set thereof cannot be mated with an opposite connector in any other set thereof having a larger number of pairs of terminals. In other words, there could be serious problems if a smaller sized connector would be connected inadvertently or erroneously to a larger sized connector.
Problems are encountered in attempting to employing keying schemes to electrical connector systems described immediately above, particularly wherein the plurality of sets of connectors in the electrical connector system employ silos and receptacles at the mating interface between the connectors in each set. These problems arise particularly in high density and/or miniaturized electrical connectors wherein the terminals are very closely spaced in a compact array. It is difficult to provide keying structures on the silos and/or in the receptacles because the walls thereof are very thin when using particular configurations of terminals. This invention also is directed to solving those problems by providing a unique keying system for sets of electrical connectors which use silos and receptacles at their mating interfaces.
This invention is directed to solving such problems and satisfying the need for such a keying system.